[...]
Davison: "... Everyone accepts gravitation and the equations associated with
it, yet no one yet understands the cause of gravity. ..."
DNAunion: Being a physics instructor, Bowman could surely shed more light on
this than I can, and might even show that I am wrong, but I thought Einstein
*did explain* the cause of gravity in his theory of general relativity.
In his generalizing of his theory of special relativity (which deals only
with reference frames in uniform motion) to accelerated motion, Einstein
stated that matter and energy warp four-dimensional spacetime, and that
matter follows the straightest possible line through spacetime (which may not
be a Euclidean straight line, because of the curvature of the 4 dimensions),
that is, as has been said, "matter gets its marching orders locally". The
more matter or energy concentrated in a particular area, the more the
surrounding spacetime is curved/warped, correlating to what Newton would call
a greater gravitational attraction in that area (Einstein does not consider
gravity to be a true force because it can be transformed away: the affects of
gravity are indistinguishable from the affects of acceleration, according to
his equivalence principle, as Einstein explained in several thought
experiments involving free-falling and intergalactic elevators).
So while Newton would have simply stated that two massive objects attracted
each other more strongly than two less massive objects - but without giving a
reason - Einstein would have *explained* that the greater attraction was due
to the greater curvature of spacetime by the more massive objects.
So isn't the *cause* of gravity the curvature of spacetime generated by
matter and energy?
This archive was generated by hypermail 2b29 : Mon Nov 06 2000 - 18:36:58 EST